I think the obvious next move is to place a "1" in r3c7. There isn't any "1" in column 7, yet, and it can't go anywhere else because of "1"'s in r2c2, r1c4, and r7c3.

This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there).

I think the obvious next move is to place a "1" in r3c7. There isn't any "1" in column 7, yet, and it can't go anywhere else because of "1"'s in r2c2, r1c4, and r7c3.

This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there).

<<This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there). >>

The same logic you used was the same I used to get the 7 in r3c5. I mis-labeled the column/row in my original post. Regardless, once you get the 1 and/or the 7, the puzzle is done.

You're right -- Holly had the hard part done, and was probably just too tired to notice that she was almost there.

I didn't quite understand what you said about the two pairs in column 1. I mean, I saw the two pairs, but couldn't quite follow your explanation about how that led to a "7" in row three. Could you explain that a bit more clearly?

This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there).

Sorry for bringing up that ancient puzzle, but how does "this" lead immediately to a 7 in r3c5? Please, help.

This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there).

Sorry for bringing up that ancient puzzle, but how does "this" lead immediately to a 7 in r3c5? Please, help.

I suppose you see why the "1" has to go in r3c7. (It has to go in the top right 3x3 box somewhere, and it can't fit in r1c9, in particular, because that would make it impossible to place a "1" in the middle right 3x3 box).

Now analyze the first column. The only numbers missing are {2, 6, 7, 8}. There are both a "2" and an "8" already placed in row 2 and in row 9, Therefore the pair {6, 7} must fit in r2c1 & r9c1, and the {2, 8} pair must occupy r1c1 & r3c1.

But now there's just one place left to place a "7" in row 3 -- at r3c5 -- because of the "7"s at r7c6 & r8c8.

This leads immediately to a "7" in r3c5, which implies a "1" in r5c5 (the center square) which in turn implies a "7" in r5c9 (the "7" that someone somewhere referred to, without quite explaining how to get there).

Sorry for bringing up that ancient puzzle, but how does "this" lead immediately to a 7 in r3c5? Please, help.

I suppose you see why the "1" has to go in r3c7. (It has to go in the top right 3x3 box somewhere, and it can't fit in r1c9, in particular, because that would make it impossible to place a "1" in the middle right 3x3 box).

Now analyze the first column. The only numbers missing are {2, 6, 7, 8}. There are both a "2" and an "8" already placed in row 2 and in row 9, Therefore the pair {6, 7} must fit in r2c1 & r9c1, and the {2, 8} pair must occupy r1c1 & r3c1.

But now there's just one place left to place a "7" in row 3 -- at r3c5 -- because of the "7"s at r7c6 & r8c8.

I hope that helps. dcb

David, thank you VERY MUCH. It was just in front of me, but I couldn't see it.